Interferometric observations for oxygen-containing organic molecules toward Orion-KL.

ABSTRACT

High spatial resolution observations (approximately 5") were made for the 3 mm transitions of methanol (CH3OH), methyl formate (HCOOCH3), and dimethyl ether [(CH3)2O] toward Orion-KL using the Nobeyama Millimeter Array. The 15(3)-14(4) A- CH3OH emission appears to be elongated along the line connecting IRc2 and "the southern condensation (SC)", which may suggest a relation between methanol and the outflow from IRc2. The HCOOCH3 (7(1,6)-6(1,5)) and (CH3)2O (15(2,13)-15(1,14)) emissions appear to be well concentrated toward SC with an angular size of approximately 6".5 (at the 2 sigma level). There also exists another oxygen-rich condensation to the west of IRc2 (angular size approximately 4".5) having column densities of HCOOCH3 and (CH3)2O comparable to those of SC. We derive the total column densities 6.8 x 10(16) cm-2, 1.4 x 10(16) cm-2 and 2.7 x 10(16) cm-2 for CH3OH, HCOOCH3, and (CH3)2O, respectively, at the core of SC.